Won't start with Choke on

you say 1976 R60/6 - I have same

Choke as you call it is much different than CV carbs
other posts are talking about

You say you did not take choke apart - long storage
and much crud from bad gas will have it all plugged up

Choke is verticle slider plug with soft material stopper in bottom
end which can be dissolved by carb cleaner or otherwise crumble
and plug up jet hole in bottom of choke slider bore

When in running position slider plug is pushed all way to
bottom of bore and soft end plugs enrichening port

When in choke position slider plug is pulled up away from
enrichening port to allow more fuel to flow to engine when cold

44006 said:

you say 1976 R60/6 - I have same

Choke as you call it is much different than CV carbs
other posts are talking about

You say you did not take choke apart - long storage
and much crud from bad gas will have it all plugged up

Choke is verticle slider plug with soft material stopper in bottom
end which can be dissolved by carb cleaner or otherwise crumble
and plug up jet hole in bottom of choke slider bore

When in running position slider plug is pushed all way to
bottom of bore and soft end plugs enrichening port

When in choke position slider plug is pulled up away from
enrichening port to allow more fuel to flow to engine when cold

Click to expand...

Thanks for weighing in -- you are right the slide carbs are MUCH different than the CVs. I'm intimately familiar with this choke system and how it works. When I said I didn't take the choke apart I'm talking about the operation system. There is a difference between taking the choke mechanism apart and thoroughly cleaning the carburetor and the passage ways. To that end the carbs and all passage ways and jets (including those of the choke circuit) have been completely cleaned upon removal from the bike (can't remove the carbs from the bike without disconnecting the choke mechanism).

There is no need to dismantle the choke operators (Cables, springs, pistons, choke pads, actuation lever, etc.) in order to make sure they are working as they should. This is done with a visual inspection.

In speaking to the head mechanic at the BMW dealership yesterday I learned that these bikes, especially the R60s, were set up to run rich. They're jetted rich and naturally run that way. He said it is not surprising that the bike won't start with the choke on in the warm weather; adding an exceptionally rich mixture of fuel in warm, HUMID (we're around 75-85% humidity right now) weather makes it even worse. I can go pull the slides on my bike after sitting all night and they will be wet with fuel as will the bottom of the carb throat.

Finally, the problem I'm having is most definitely not that the choke circuit is not passing enough fuel; it's too much. When the choke is on full or the half-stop there is simply too much fuel coming into the mix. With the choke on in humid, 80+ degree F temps the bike does not start and everything looks, smells, acts and feels flooded. My advice to anyone who has similar problems to these is: when we hear hoof beats think horses not zebras.

so how about the diameter of the jet in the bottom of the choke
slider slug assembly - did someone enlarge it by running some
kind of wire or pipecleaner tool through it?

44006 said:

so how about the diameter of the jet in the bottom of the choke
slider slug assembly - did someone enlarge it by running some
kind of wire or pipecleaner tool through it?

Click to expand...

They don't come out so it's very hard to tell if that's the case. It's also hard to see it. Using a flash light there are no scratches or nicks in either of them.